1. Field of the Invention
This invention relates to apparatus for preventing a vehicle from being driven away from a loading bay during loading/unloading, and a method for the same purpose.
2. Description of the Related Art
The normal sequence of events is that a vehicle (a semi-trailer, a drawbar trailer, or a lorry) is driven up to a loading bay and the driver contacts staff in the building. The loading bay has a door, usually of the ‘up and over’ type, and a dock leveller. The dock leveller is a powered ramp which is adjusted in height to accommodate differences in vehicle loading heights and to enable forklifts to drive from the building into the vehicle. To prevent accidents several safeguards are currently employed. Current systems include:                Traffic lights, some of which are linked to the dock leveller. This does not prevent the driver from moving off but relies upon him obeying the lights. These systems are quite expensive.        A traffic barrier system which retains the vehicle at the loading bay until a barrier is raised. This also relies upon correct procedure and is expensive.        An inbuilt wheel blocking device which is installed in the ground at each bay and which is raised to prevent the vehicle from leaving until loading is complete. This is very expensive and also relies upon correct procedure to be effective.        A wheel clamp which is fitted when the vehicle arrives and which provides a physical and visual barrier to indicate to the driver and he/she should not drive off. This also relies upon procedures and is cumbersome to operate.        